The quantities and materials of the chiefs' gifts in Numbers 7 are all significant, even if we don't have a full understanding of them today.

Scripture gives us many hints as to what these things mean, but rarely spells it out. Flour and oil is flesh and spirit. Silver is atonement and blood. Incense is prayer. The bull, ram, and sheep might be an allusion to the three patriarchs. The two peace offerings could be an allusion to Moses and Aaron, two witnesses to the covenant represented in the Tabernacle. etc